Tobacco exposure is one of world's leading causes of death and illness and traditionally affected more men than women. However, the twenty first century burden of smoking might become disproportionally larger in women than in men for two reasons. First, as the smoking epidemic reached its peak decades earlier in men than in women, previous studies on female smoking-related hazards are highly likely have underestimated the full eventual impact of smoking on mortality in women because of the lengthy time lag between smoking uptake and disease onset in middle and old age. Second, findings from large contemporary studies suggest that the full health hazards of prolonged smoking are at least as great as, and potentially even greater, among women who smoke compared with men who smoke. Moreover, quitting smoking is equally beneficial in men and women all across the world. Future studies that attempt to identify the potential mechanisms responsible for the greater risk observed in women compared with men who smoke are warranted. Clinically, physicians and health professionals should be encouraged to further increase their efforts at promoting smoking cessation in men and women.